Until now, there have been proposals of devices and methods for the visual confirmation of volumetric images through 2D (two-dimensional) images formed inside a display apparatus, however, visual fields in which the volumetric images can be visually confirmed are narrow, and there are problems such as a need for special glasses for the visual confirmation of volumetric images.
Therefore, for example, in Patent Literature 1, a system for displaying a volumetric image directly in a space (a physically deep space) inside a display apparatus and a method thereof are proposed. Since this volumetric image is formed from electronic data, there is no limitation on an obtained volumetric image, enabling an observer to see an image based on the position where the observer views the image from. For example, the right side of an image can be visually confirmed when the image is viewed from the right, and there is also an advantage of being able to look inside from above.
Moreover, for example, in Patent Literatures 2 and 3, devices which use an actual object and display a real image (volumetric image) thereof in a free space and methods thereof are disclosed. This volumetric image is formed in a free space, therefore, there is no limitation in the size of the volumetric image (e.g., a volumetric image equal in size to an object can be displayed), and there is an advantage of being able to touch the volumetric image with hands as well (in actuality, volumetric images are unsubstantial and hands will slip through).